The calibration unit is used to calibrate and characterize the SPIP spectrograph in order to ensure the highest possible RV (Radial Velocity) stability over the short term (one night) and the long term (several years). To ensure this objective, the calibration unit provides light using different lamps to perform the following calibrations:
- location and geometry of the spectral orders;
- determination of flat field (pixel response) and blaze profile response;
- determination of wavelength calibration;
- determination of the radial speed setpoint (zero point);
- provide a “cold finger” to avoid thermal emissivity.
The calibration unit has two fiber connections. The first connects the unit directly to the spectrograph and the second connects the calibration beam through the Cassegrain unit of the Bernard Lyot telescope (TBL) at the Pic du Midi Observatory.
